Energy-Efficient Sensing Mechanism for Licensed-Assisted Access Under Non-Saturated Traffic Condition

Abstract

This paper investigates the energy-efficiency oflicensed-assisted access (LAA) which enable long-term evolutionsystems to operate in unlicensed spectrum. Since Wi-Fi with802.11 n/ac is a typical radio access technology in the unlicensedspectrum, we consider a scenario that the LAA small-cell basestations (SCBSs) are deployed together with Wi-Fi access points.We propose three different listen-before-talk (LBT) schemesaccording to the channel sensing mechanisms for LAA SCBC,and establish Markov chain models for each scheme under nonsaturatedtraffic condition. Using these analytical models, theenergy-efficiencies of LAA SCBSs that perform the differentLBT schemes are investigated. We also propose the algorithmto obtain the optimal contention window size of LAA SCBSsby which total energy-efficiency of networks is maximized whilesatisfying the required energy-efficiency of both LAA and Wi-Finetworks. Numerical results show that the LBT scheme whichhas an efficient channel sensing mechanism outperforms theother LBT schemes for the energy-efficiency perspective.edspectrum, we consider a scenario that the LAA small-cell basestations (SCBSs) are deployed together with Wi-Fi access points.We propose three different listen-before-talk (LBT) schemesaccording to the channel sensing mechanisms for LAA SCBC,and establish Markov chain models for each scheme under nonsaturatedtraffic condition. Using these analytical models, theenergy-efficiencies of LAA SCBSs that perform the differentLBT schemes are investigated. We also propose the algorithmto obtain the optimal contention window size of LAA SCBSsby which total energy-efficiency of networks is maximized whilesatisfying the required energy-efficiency of both LAA and Wi-Finetworks. Numerical results show that the LBT scheme whichhas an efficient channel sensing mechanism outperforms theother LBT schemes for the energy-efficiency perspective.